Which genus of mosquito is the most important vector of West Nile virus?

• A. Aedes
• B. Culex
• C. Anopheles
• D. Mansonia

Answer: (B)

The main concept here is which mosquito group drives West Nile virus transmission. West Nile is primarily spread by Culex mosquitoes. These species are especially effective vectors because they feed on birds, which are the virus’s reservoir, and then occasionally bite humans, enabling transmission to people. In many parts of North America, Culex, such as Culex pipiens and Culex quinquefasciatus, are common in urban and suburban settings and breed in standing water with organic material found in storm drains and other polluted habitats. Their nocturnal or crepuscular activity also aligns with times when humans are outdoors or indoors at risk, increasing contact opportunities.

Other genera are associated with different diseases: Aedes mosquitoes are the main vectors for viruses like dengue, Zika, and chikungunya; Anopheles transmit malaria; Mansonia can be involved with certain filarial parasites. But for West Nile virus, the most important vector is the genus Culex. This understanding guides control strategies toward reducing Culex larval habitats and suppressing adult Culex populations to cut transmission.